Unfortunately, the Tempest boards have seen their last repair, which is why I went ahead and decided
to run it in MAME. I left the original boards in there for posterity though- but there's no way I can test the spinner.
It's been in storage so long I can't remember if the spinner was a problem before or not.

Well, I'm running out of possibilities, and I guess the sensor being bad could be one.
If we were to assume that the optical board/sensor were bad, would I be able to theoretically
replace all of the components on it and expect it to work again? I don't want to shell out over $50
for a used Tempest spinner...I've already got one! (b/c who knows what 'untested' could really mean, right?)